A navigation device which provides a vehicle driver with route information for a destination or the like may sometimes have a so-called head unit function which allows functions of an external device such as a smartphone to be used through a display device or a speaker (a so-called human-machine interface (HMI) device) included in the navigation device when the external device is connected to the navigation device.
By connecting a user's smartphone to a navigation device having such a head unit function via an information communication bus such as a USB, it is possible to use, for example, a navigation function provided by the connected smartphone executing an application/program instead of a navigation function of the navigation device.
This allows the user to selectively utilize a familiar smartphone or the in-vehicle navigation device according to applications and preferences. However, new problems may arise since the same (or the same type of) “navigation function” may be able to be used through a plurality of devices (including the in-vehicle navigation device and the smartphone).
For example, when a driver, i.e., a user, uses his or her smartphone with a destination set therein by connecting it to an in-vehicle navigation device having a head unit function after setting another destination in the in-vehicle navigation device and starting navigation with the in-vehicle navigation device, it is difficult for the user to immediately determine whether route guidance information (navigation information) currently provided from the in-vehicle navigation device is route guidance information for the destination set in the navigation device or route guidance information for the destination set in the smartphone, which may cause confusion or uneasiness in the user.
In-vehicle GPS devices used in in-vehicle navigation devices and GPS devices used in smartphones often have different positioning accuracies. In general, in-vehicle GPS devices are more accurate. The accuracy and update frequency of map information used to generate route information or the like are also often different between an in-vehicle navigation device and a smartphone. Since there is a difference in the accuracy of route guidance information between an in-vehicle navigation device and a smartphone, when using the smartphone by connecting it to the in-vehicle navigation device as described above, the user may misread the accuracy of route information, leading to deviation from the target route, even if the same destination has been set in both the in-vehicle navigation device and the smartphone if it is not possible to identify which of the in-vehicle navigation device and the smartphone is outputting route guidance information.
Further, when the user desires to order inspection or repair of a navigation function that has been used due to a malfunction occurring therein, the user cannot specify the device of which he or she should order inspection or repair to correct the malfunction and also cannot correctly select a repairer to be ordered if it is not possible to identify whether the navigation function of the in-vehicle navigation device or the navigation function of the smartphone was being used at the time of occurrence of the malfunction.
Therefore, it is necessary for the user to easily determine (identify) whether a navigation function included in an in-vehicle navigation device or a navigation function included in a smartphone is being used.
An in-vehicle device which communicates with a mobile phone and displays display data that is being displayed on a screen of the mobile phone on an in-vehicle display device is known in the art (Patent Literature 1). Here, it can be assumed that, in the case in which the navigation device having the head unit function described above employs the configuration of this in-vehicle device, display data that is being displayed on the screen of the smartphone is displayed on the in-vehicle display when the navigation function of the smartphone is used and display data of the navigation function included in the in-vehicle navigation device is displayed on the in-vehicle display when the in-vehicle navigation device is used. In this case, it is possible to identify whether the device currently used for navigation is the in-vehicle navigation device or the smartphone from the difference in the display screen displayed on the in-vehicle display.
However, if the devices provide the same or the same type of navigation function even if the devices providing the navigation function are different, a lot of common information such as “map information” and “route display” is displayed on the display, which may make such identification difficult at a glance. Furthermore, in general, an in-vehicle display having a screen size suitable for displaying map information or the like is often disposed at the center of a dashboard and it is difficult for the driver to identify slight differences in the display screen by turning his or her gaze to such an in-vehicle display disposed at the center of the dashboard, which is also undesirable from the viewpoint of safe driving.
A navigation system which displays icons indicating route change directions according to route guidance information (i.e., performs so-called turn-by-turn display) on the screen of an instrument such as a speedometer which is easily seen by the driver at a timing before route change is needed is also known (Patent Literature 2).
However, since the route change display is provided in the form of icons in this system, when the system is applied to an environment in which route guidance information can be provided by a plurality of different devices such as an in-vehicle navigation device and a smartphone, it is very difficult to identify, from the route change display provided in the form of icons, which device has provided the route guidance information on which the route change display is based.